when i use the model's normal , the result is fine ( there are dark areas and lit areas , as i would expect from a simple lambert diffuse shader )
but when i use a normal map , the dark areas gets lit!
i want to use a normal map and still get correct diffuse lighting like these examples
here is the code with and without normal mapping
and here is the code that uses the normal map
Vertex Shader
varying vec3 normal,lightDir;
attribute vec3 vertex,normalVec,tangent;
attribute vec2 UV;
void main(){
gl_TexCoord[0] = gl_TextureMatrix[0] * vec4(UV,0.0,0.0);
normal = normalize (gl_NormalMatrix * normalVec);
vec3 t = normalize (gl_NormalMatrix * tangent);
vec3 b = cross (normal, t);
vec3 vertexPosition = normalize(vec3(gl_ModelViewMatrix * vec4(vertex,1.0)));
vec3 v;
v.x = dot (lightDir, t);
v.y = dot (lightDir, b);
v.z = dot (lightDir, normal);
lightDir = normalize (v);
lightDir = normalize(vec3(1.0,0.5,1.0) - vertexPosition);
gl_Position = gl_ModelViewProjectionMatrix*vec4(vertex,1.0);
}
Fragment Shader
vec4 computeDiffuseLight (const in vec3 direction, const in vec4 lightcolor, const in vec3 normal, const in vec4 mydiffuse){
float nDotL = dot(normal, direction);
vec4 lambert = mydiffuse * lightcolor * max (nDotL, 0.0);
return lambert;
}
varying vec3 normal,lightDir;
uniform sampler2D textures[8];
void main(){
vec3 normalVector = normalize( 2 * texture2D(textures[0],gl_TexCoord[0].st).rgb - 1 );
vec4 diffuse = computeDiffuseLight (lightDir, vec4(1,1,1,1) , normalVector, vec4(0.7,0.7,0.7,0));
gl_FragColor = diffuse ;
}
Note: the actual normal mapping works correctly as seen in the specular highlights
i used Assimp to load the model ( md5mesh ) and calculated the tangents using Assimp too , then sent it to the shaders as an attribute
here is a link to the code and screenshots of the problem
https://dl.dropboxusercontent.com/u/32670019/code%20and%20screenshots.zip
is that a problem in the code or am i having a misconception ?
Updated code and screenshots
https://dl.dropboxusercontent.com/u/32670019/updated%20code%20and%20screenshots.zip
now the normal map works with the diffuse , but the diffuse alone is not correct
For Answer, see below.
Quick (possibly wrong) observation:
The line
vec3 normalVector = normalize( 2 * texture2D(textures[0],gl_TexCoord[0].st).rgb - 1 );
in your fragment shader correctly rescales your normal to allow for negative values. If your normal map is incorrect, negative values might occur where you do not want them (your Y axis I presume). Negative values in a normal can result in reversed lighting.
My question to you: Is your normal map correct?
ANSWER: After a bit of discussion we found the problem, I've edited this post to keep the thread clean, the solution to Darko's problems are in the comments here. It came down to uninitialized varying called lightDir.
Original comment:
lightDir = normalize (v); lightDir = normalize(vec3(1.0,0.5,1.0) - vertexPosition); This is strange, you overwrite it instantly, is this wrong? you dont seem to keep the correctly translated lightDir... Or am I crazy... Also this lightDir is a varying, but you don't set it at all. So you calculate a v vector from nothing?
Related
First of all, I must apologize for posting yet another question on this subject (there are a lot already!). I did search for other related questions and answers, but unfortunately none of them showed me the solution. Now I'm desperate! :D
It is worth mentioning that the code posted below gives a satisfying 'bumpy' effect. It is the scene enlightenment that seems to be wrong.
The scene: is dead simple! A cube in the center, a light source rotating around it (parallel to the ground) and above.
My approach is to start from my basic light shader, which gives me adequate outputs (or so I think!). The first step is to modify it to do the calculations in tangent space, then use the normal extracted from a texture.
I tried to comment the code nicely, but in short I have two questions:
1) Doing only basic lighting (no normal mapping), I expect the scene to look exactly the same, with or without transforming my vectors into tangent space with the TBN matrix. Am I wrong?
2) Why do I get incorrect enlightenment?
A couple of screenshots to give you an idea (EDITED) - following LJ's comment, I am no longer summing normals and tangent per vertex/face. Interestingly, it highlights the issue (see on the capture, I have marked how the light moves).
Basically it is as if the cube was rotated 90 degrees to the left, or, as if the light was turing vertically instead of horizontally
Result with normal mapping:
Version with simple light:
Vertex shader:
// Information about the light.
// Here we care essentially about light.Position, which
// is set to be something like vec3(cos(x)*9, 5, sin(x)*9)
uniform Light_t Light;
uniform mat4 W; // The model transformation matrix
uniform mat4 V; // The camera transformation matrix
uniform mat4 P; // The projection matrix
in vec3 VS_Position;
in vec4 VS_Color;
in vec2 VS_TexCoord;
in vec3 VS_Normal;
in vec3 VS_Tangent;
out vec3 FS_Vertex;
out vec4 FS_Color;
out vec2 FS_TexCoord;
out vec3 FS_LightPos;
out vec3 FS_ViewPos;
out vec3 FS_Normal;
// This method calculates the TBN matrix:
// I'm sure it is not optimized vertex shader code,
// to have this seperate method, but nevermind for now :)
mat3 getTangentMatrix()
{
// Note: here I must say am a bit confused, do I need to transform
// with 'normalMatrix'? In practice, it seems to make no difference...
mat3 normalMatrix = transpose(inverse(mat3(W)));
vec3 norm = normalize(normalMatrix * VS_Normal);
vec3 tang = normalize(normalMatrix * VS_Tangent);
vec3 btan = normalize(normalMatrix * cross(VS_Normal, VS_Tangent));
tang = normalize(tang - dot(tang, norm) * norm);
return transpose(mat3(tang, btan, norm));
}
void main()
{
// Set the gl_Position and pass color + texcoords to the fragment shader
gl_Position = (P * V * W) * vec4(VS_Position, 1.0);
FS_Color = VS_Color;
FS_TexCoord = VS_TexCoord;
// Now here we start:
// This is where supposedly, multiplying with the TBN should not
// change anything to the output, as long as I apply the transformation
// to all of them, or none.
// Typically, removing the 'TBN *' everywhere (and not using the normal
// texture later in the fragment shader) is exactly the code I use for
// my basic light shader.
mat3 TBN = getTangentMatrix();
FS_Vertex = TBN * (W * vec4(VS_Position, 1)).xyz;
FS_LightPos = TBN * Light.Position;
FS_ViewPos = TBN * inverse(V)[3].xyz;
// This line is actually not needed when using the normal map:
// I keep the FS_Normal variable for comparison purposes,
// when I want to switch to my basic light shader effect.
// (see later in fragment shader)
FS_Normal = TBN * normalize(transpose(inverse(mat3(W))) * VS_Normal);
}
And the fragment shader:
struct Textures_t
{
int SamplersCount;
sampler2D Samplers[4];
};
struct Light_t
{
int Active;
float Ambient;
float Power;
vec3 Position;
vec4 Color;
};
uniform mat4 W;
uniform mat4 V;
uniform Textures_t Textures;
uniform Light_t Light;
in vec3 FS_Vertex;
in vec4 FS_Color;
in vec2 FS_TexCoord;
in vec3 FS_LightPos;
in vec3 FS_ViewPos;
in vec3 FS_Normal;
out vec4 frag_Output;
vec4 getPixelColor()
{
return Textures.SamplersCount >= 1
? texture2D(Textures.Samplers[0], FS_TexCoord)
: FS_Color;
}
vec3 getTextureNormal()
{
// FYI: the normal texture is always at index 1
vec3 bump = texture(Textures.Samplers[1], FS_TexCoord).xyz;
bump = 2.0 * bump - vec3(1.0, 1.0, 1.0);
return normalize(bump);
}
vec4 getLightColor()
{
// This is the one line that changes between my basic light shader
// and the normal mapping one:
// - If I don't do 'TBN *' earlier and use FS_Normal here,
// the enlightenment seems fine (see second screenshot)
// - If I do multiply by TBN (including on FS_Normal), I would expect
// the same result as without multiplying ==> not the case: it looks
// very similar to the result with normal mapping
// (just has no bumpy effect of course)
// - If I use the normal texture (along with TBN of course), then I get
// the result you see in the first screenshot.
vec3 N = getTextureNormal(); // Instead of 'normalize(FS_Normal);'
// Everything from here on is the same as my basic light shader
vec3 L = normalize(FS_LightPos - FS_Vertex);
vec3 E = normalize(FS_ViewPos - FS_Vertex);
vec3 R = normalize(reflect(-L, N));
// Ambient color: light color times ambient factor
vec4 ambient = Light.Color * Light.Ambient;
// Diffuse factor: product of Normal to Light vectors
// Diffuse color: light color times the diffuse factor
float dfactor = max(dot(N, L), 0);
vec4 diffuse = clamp(Light.Color * dfactor, 0, 1);
// Specular factor: product of reflected to camera vectors
// Note: applies only if the diffuse factor is greater than zero
float sfactor = 0.0;
if(dfactor > 0)
{
sfactor = pow(max(dot(R, E), 0.0), 8.0);
}
// Specular color: light color times specular factor
vec4 specular = clamp(Light.Color * sfactor, 0, 1);
// Light attenuation: square of the distance moderated by light's power factor
float atten = 1 + pow(length(FS_LightPos - FS_Vertex), 2) / Light.Power;
// The fragment color is a factor of the pixel and light colors:
// Note: attenuation only applies to diffuse and specular components
return getPixelColor() * (ambient + (diffuse + specular) / atten);
}
void main()
{
frag_Output = Light.Active == 1
? getLightColor()
: getPixelColor();
}
That's it! I hope you have enough information and of course, your help will be greatly appreciated! :) Take care.
I am experiancing a very similar problem, and i can not explain why the lighting doesn't work right, but i can answer your first question and at the very least explain how i somehow got lighting working acceptably (though your problem may not necesarrily be the same is mine).
Firstly in theory if you tangents and bitangents are calculated correctly, then you should get exactly the same lighting result when doing the calculation in tangentspace with a tangentspace normal [0,0,1].
Secondly while it is common knowledge that you should transform your normals from model to cameraspace by multiplying by inverse transpose model-view matrix as explained by this tutorial, i found that the problem with the lighting being transformed wrong can be solved if you transform the normal tangent by the model-view matrix rather than the inverse transpose model-view. Ie use normalMatrix = mat3(W); instead of normalMatrix = transpose(inverse(mat3(W)));.
In my case this did »fix« the problems with the light, but i don't know why this fixed it, but i make no guarantee that it does not (in fact i assume that it does) introduce other problems with the shading
I've been trying to make a basic static point light using shaders for an LWJGL game, but it appears as if the light is moving as the camera's position is being translated and rotated. These shaders are slightly modified from the OpenGL 4.3 guide, so I'm not sure why they aren't working as intended. Can anyone explain why these shaders aren't working as intended and what I can do to get them to work?
Vertex Shader:
varying vec3 color, normal;
varying vec4 vertexPos;
void main() {
color = vec3(0.4);
normal = normalize(gl_NormalMatrix * gl_Normal);
vertexPos = gl_ModelViewMatrix * gl_Vertex;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}
Fragment Shader:
varying vec3 color, normal;
varying vec4 vertexPos;
void main() {
vec3 lightPos = vec3(4.0);
vec3 lightColor = vec3(0.75);
vec3 lightDir = lightPos - vertexPos.xyz;
float lightDist = length(lightDir);
float attenuation = 1.0 / (3.0 + 0.007 * lightDist + 0.000008 * lightDist * lightDist);
float diffuse = max(0.0, dot(normal, lightDir));
vec3 ambient = vec3(0.4, 0.4, 0.4);
vec3 finalColor = color * (ambient + lightColor * diffuse * attenuation);
gl_FragColor = vec4(finalColor, 1.0);
}
If anyone's interested, I ended up finding the solution. Removing the calls to gl_NormalMatrix and gl_ModelViewMatrix solved the problem.
The critical value here, lightPos, was being set as a function of vertexPos, which you have expressed in screen space (this happened because its original world space form was multiplied by modelView). Screen space stays with the camera, not anything in the 3D world. So to have a non-moving light source with respect to some absolute point in world space (like [4.0, 4.0, 4.0]), you could just leave your object's points in that space as you found out.
But getting rid of modelview is not a good idea, since the whole point of the model matrix is to place your objects where they belong (so you can re-use your vertex arrays with changes only to the model matrix, instead of burdening them with specifying every single shape's vertex positions from scratch).
A better way is to perform the modelView multiplication on both vertexPos AND lightPos. This way you're treating lightPos as originally a quantity in world space, but then doing the comparison in screen space. The math to get light intensities from normals will work out to the same in either space and you'll get a correct looking light source.
I am trying to create a stucco texture similar to the image below in an GLSL fragment and vertex shader.
I know there are multiple ways to accomplish this. However, I want to focus on perturbing the surface normal in the fragment shader based on the values I receive from the noise function.
My thought process is the following..
Send the noise function my current position scaled by some scalar.
Once I have my noise, I can then perturb the surface normal and use it with my Phong shading model.
However, I'm not sure where I go from there.
Here is what I have so far.
Vertex shader - Calculate Tangent is a helper method to build the tangent vector based on the object norm.
#version 120
varying vec3 LightDir;
varying vec3 EyeDir;
varying vec3 MCPoint;
main(){
MCPoint = gl_Vertex.xyz;
EyeDir = vec3(gl_ModelViewMatrix * gl_Vertex);
vec3 LightPosition = gl_LightSource[0].position.xyz;
vec3 tangent = calculateTangent(gl_Normal);
// Building the Tangent matrix
vec3 n = normalize(gl_NormalMatrix * gl_Normal);
vec3 t = normalize(gl_NormalMatrix * tangent);
vec3 b = cross(n, t);
vec3 v;
v.x = dot(LightPosition, t);
v.y = dot(LightPosition, b);
v.z = dot(LightPosition, n);
LightDir = normalize(v);
v.x = dot(gl_vertex.xyz, t);
v.y = dot(gl_Vertex.xyz, b);
v.z = dot(gl_Vertex.xyz, n);
EyeDir = normalize(v);
gl_Position = ftransform();
}
Fragment Shader - so far...
#version 120
varying vec3 LightDir;
varying vec3 EyeDir;
varying vec3 MCPoint;
main(){
vec2 _noisexy = noise2(MCPoint.xy * 1.65);
// offset normal
// Calculate phong shading based on LightDir, EyeDir, & Newly distorted Normal
gl_FragColor= intensity * vec4(my_surface_color, 1.0);
}
Now, to my actual questions.
What normal do I offset? Would I offset the object normal? I have been reading that the bump mapping should take place in object space.
What is the best way to apply the offset to the normal?
Some system info:
Mac OSX - OpenGL 3.2 - Shader must be able to work on older macs that do not have the new 3.2 support.
Pixel based lighting is a common issue in many OpenGL applications, as the standard OpenGL lighting has very poor quality.
I want to use a GLSL program to have per-pixel based lighting in my OpenGL program instead of per-vertex. Just Diffuse lighting, but with fog, texture and texture-alpha at least.
I started with this shader:
texture.vert:
varying vec3 position;
varying vec3 normal;
void main(void)
{
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_FrontColor = gl_Color;
gl_TexCoord[0] = gl_MultiTexCoord0;
normal = normalize(gl_NormalMatrix * gl_Normal);
position = vec3(gl_ModelViewMatrix * gl_Vertex);
}
texture.frag:
uniform sampler2D Texture0;
uniform int ActiveLights;
varying vec3 position;
varying vec3 normal;
void main(void)
{
vec3 lightDir;
float attenFactor;
vec3 eyeDir = normalize(-position); // camera is at (0,0,0) in ModelView space
vec4 lightAmbientDiffuse = vec4(0.0,0.0,0.0,0.0);
vec4 lightSpecular = vec4(0.0,0.0,0.0,0.0);
// iterate all lights
for (int i=0; i<ActiveLights; ++i)
{
// attenuation and light direction
if (gl_LightSource[i].position.w != 0.0)
{
// positional light source
float dist = distance(gl_LightSource[i].position.xyz, position);
attenFactor = 1.0/( gl_LightSource[i].constantAttenuation +
gl_LightSource[i].linearAttenuation * dist +
gl_LightSource[i].quadraticAttenuation * dist * dist );
lightDir = normalize(gl_LightSource[i].position.xyz - position);
}
else
{
// directional light source
attenFactor = 1.0;
lightDir = gl_LightSource[i].position.xyz;
}
// ambient + diffuse
lightAmbientDiffuse += gl_FrontLightProduct[i].ambient*attenFactor;
lightAmbientDiffuse += gl_FrontLightProduct[i].diffuse * max(dot(normal, lightDir), 0.0) * attenFactor;
// specular
vec3 r = normalize(reflect(-lightDir, normal));
lightSpecular += gl_FrontLightProduct[i].specular *
pow(max(dot(r, eyeDir), 0.0), gl_FrontMaterial.shininess) *
attenFactor;
}
// compute final color
vec4 texColor = gl_Color * texture2D(Texture0, gl_TexCoord[0].xy);
gl_FragColor = texColor * (gl_FrontLightModelProduct.sceneColor + lightAmbientDiffuse) + lightSpecular;
float fog = (gl_Fog.end - gl_FogFragCoord) * gl_Fog.scale; // Intensität berechnen
fog = clamp(fog, 0.0, 1.0); // Beschneiden
gl_FragColor = mix(gl_Fog.color, gl_FragColor, fog); // Nebelfarbe einmischen
}
Comments are german because it's a german site where this code was posted, sorry.
But all this shader does is make everything very dark. No lighting effects at all - yet the shader codes compile. If I only use GL_LIGHT0 in the fragment shader, then it seems to work, but only reasonable for camera facing polygons and my floor polygon is just extremely dark. Also quads with RGBA textures show no sign of transparency.
I use standard glRotate/Translate for the Modelview matrix, and glVertex/Normal for my polygons. OpenGL lighting works fine apart from the fact that it looks ugly on very large surfaces. I triple checked my normals, they are fine.
Is there something wrong in the above code?
OR
Tell me why there is no generic lighting Shader for this actual task (point based light with distance falloff: a candle if you will) - shouldn't there be just one correct way to do this? I don't want bump/normal/parallax/toon/blur/whatever effects. I just want my lighting to perform better with larger polygons.
All Tutorials I found are only useful for lighting a single object when the camera is at 0,0,0 facing orthogonal to the object. The above is the only one found that at least looks like the thing I want to do.
I would strongly suggest you to read this article to see how the standard ADS lightning is done within GLSL.That is GL 4.0 but not a problem to adjust to your version:
Also you operate in the view (camera) space so DON"T negate the eyes vector :
vec3 eyeDir = normalize(-position);
I had pretty similar issues to yours because I also negated the eye vector forgetting that it is transformed into the view space.Your diffuse and specular calculations seem to be wrong too in the current scenario.In your place I wouldn't use data from the fixed pipeline at all ,otherwise what is the point doing it in a shader?
Here is the method to calculate diffuse and specular in the per fragment ADS point lightning:
void ads( int lightIndex,out vec3 ambAndDiff, out vec3 spec )
{
vec3 s = vec3(lights[lightIndex].Position - posOut) ;
vec3 v = normalize( posOut.xyz );
vec3 n = normalize(normOut);
vec3 h = normalize(v+s) ;// half vector (read in the web on what it is )
vec3 diffuse = ((Ka+ lights[lightIndex].Ld) * Kd * max( 0.0,dot(n, v) )) ;
spec = Ks * pow( max(0.0, dot(n,h) ), Shininess ) ;
ambAndDiff = diffuse ;
/// Ka-material ambient factor
/// Kd-material diffuse factor
/// Ks-material specular factor.
/// lights[lightIndex].Ld-lights diffuse factor;you may also add La and Ls if you want to have even more control of the light shading.
}
Also I wouldn't suggest you using the attenuation equation you have here,it is hard to control.If you want to add light radius based attenuation
there is this nice blog post:
I have a query regarding refraction.
I am using a texture image for refraction(refertest_car.png).
But somehow the texture is getting multiplied and givinga distorted image(Refer Screenshot.png)
i am using following shader.
attribute highp vec4 vertex;
attribute mediump vec3 normal;
uniformhighp mat4 matrix;
uniformhighp vec3 diffuse_color;
uniformhighp mat3 matrixIT;
uniformmediump mat4 matrixMV;
uniformmediump vec3 EyePosModel;
uniformmediump vec3 LightDirModel;
varyingmediump vec4 color;
constmediump float cShininess = 3.0;
constmediump float cRIR = 1.015;
varyingmediump vec2 RefractCoord;
vec3 SpecularColor= vec3(1.0,1.0,1.0);
voidmain(void)
{
vec3 toLight = normalize(vec3(1.0,1.0,1.0));
mediump vec3 eyeDirModel = normalize(vertex.xyz -EyePosModel);
mediump vec3 refractDir =refract(eyeDirModel,normal, cRIR);
refractDir = (matrix * vec4(refractDir, 0.0)).xyw;
RefractCoord = 0.5 * (refractDir.xy / refractDir.z) + 0.5;
vec3 normal_cal = normalize(matrixIT *normal );
float NDotL = max(dot(normal_cal, toLight), 0.0);
vec4 ecPosition = normalize(matrixMV * vertex);
vec3 eyeDir = vec3(1.0,1.0,1.0);
float NDotH = 0.0;
vec3 SpecularLight = vec3(0.0,0.0,0.0);
if(NDotL > 0.0)
{
vec3 halfVector = normalize( eyeDirModel + LightDirModel);
float NDotH = max(dot(normal_cal, halfVector), 0.0);
float specular =pow(NDotH,3.0);
SpecularLight = specular * SpecularColor;
}
color = vec4((NDotL * diffuse_color.xyz) + (SpecularLight.xyz) ,1.0);
gl_Position = matrix * vertex;
}
And
varyingmediump vec2 RefractCoord;
uniformsampler2D sTexture;
varyingmediump vec4 color;
voidmain(void)
{
lowp vec3 refractColor = texture2D(sTexture,RefractCoord).rgb;
gl_FragColor = vec4(color.xyz + refractColor,1.0);
}
Can anyone let me know the solution to this problem?
Thanks for any help.
Sorry guys i am not able to attach image.
It seems that you are calculating the refraction vector incorrectly. Hovewer, the answer to your question is already in it's title. If you are looking at ellipsoid, the rays from the view span a cone, wrapping the ellipsoid. But after the refraction, the cone may be much wider, reaching beyond the edges of your images, therefore giving texture coordinates larger than 0 - 1 and leading to texture being wrapped. So we need to take care of that as well.
First, the refraction coordinate should be calculated in vertex shader as follows:
vec3 eyeDirModel = normalize(-vertex * matrix);
vec3 refractDir = refract(eyeDirModel, normal, cRIR);
RefractCoord = normalize((matrix * vec4(refractDir, 0.0)).xyz); // no dehomog!
RefractCoord now contains refracted eye-space vectors. This counts on "matrix" being modelview matrix (that is not clear from your code, but i suspect it is). You could possibly skip normalization if you wish the shader to run faster, it shouldn't cause noticeable errors. Now a little bit of modification to your fragment shader.
vec3 refractColor = texture2D(sTexture, normalize(RefractCoord).xy * .5 + .5).rgb;
Here, using normalize() makes sure that the texture coordinates do not cause the texture to repeat.
Note that using 2D texture for refractions should be only justified by generating it on the fly (as e.g. Half-Life 2 does), otherwise one should probably use cube-map texture, which does the normalization for you and gives you color based on 3D direction - which is what you need.
Hope this helps ... (and, oh yeah, i wrote this from memory, in case there are any errors, please comment).